1. Field of the Invention
The present invention relates to a propeller structure for a hermetically sealed compressor, and more particularly to an improved propeller structure for a hermetically sealed compressor capable of enhancing an oil supply capacity and minimizing a whirling sound and a dropping noise which may occur during rotation of a piece and a propeller thereof, by gradually broadening a wing of the propeller in width from bottom to top.
2. Description of the Prior Art
As shown in FIG. 1, a conventional hermetically sealed compressor includes a hermetic container 1 having an upper and lower cells 1a, 1b, and a motor unit 3 provided in the hermetic container 1 and having a rotor 3a and a stator 3b.
An end of each of a plurality of support springs 4 is connected at a side portion along an inner periphery of the lower cell 1b, and another end of each of the support springs 4 supports a frame 2.
A crank shaft 5 having an eccentric portion 6 at an upper portion thereof is heat-inserted into the hole in the rotor 3a. A cylinder 7 is connected to an upper portion of the frame 2.
A piston 8 that horizontally shuttles in the cylinder 7 is engaged to the eccentric portion 6 of the crank shaft 5.
A valve plate 9 is attached onto an end portion of the cylinder 7, and a head cover 10 is attached onto the valve plate 9. A suction muffler (not shown) is mounted on a portion of the head cover 10.
With reference to FIG. 2, in order to suck a oil "O" in through the crank shaft 5, a cylinder type oil guide piece 11 is pressure-inserted into the crank shaft 5 which becomes rotated in accordance with the rotor 3a.
An oil suction propeller 12 is fixedly inserted into the oil guide piece 11.
At this time, respective widths of an upper and lower wings 12a, 12b comprising the suction propeller 12 are identical to each other, and the lower wing 12b of the oil suction propeller 12 is dipped in the oil "O".
The oil "O" kept in a lower portion of the hermetic container 1 is upwardly sucked by the rotation of the crank shaft 5 and scattered over the crank shaft 5. The scattered oil "O" is soaked through respective friction portions in the compressor for thereby preventing overheating and abrasion.
The oil sucking steps of the thusly constituted hermetically sealed compressor will now be described with reference to FIG. 2.
First, when an electrical power is supplied to the hermetically sealed compressor, the rotor 3a starts its rotation. Accordingly, as the crank shaft 5 heatinserted into the rotor 3a becomes rotated, the oil guide piece 11 and the oil suction propeller 12 become rotated. The thusly generated centrifugal force and an thrust force serve to upwardly suck the oil "O". At this time, the centrifugal force and the thrust force are variable depending on respective diameters of the oil guide piece 11 and the oil suction propeller 12.
That is, the more increased become the respective diameters of the upper and lower oil suction propeller wings 12a, 12b, the stronger the centrifugal force and the thrust force, and the more oil "O" is upwardly sucked. To the contrary, as the respective diameters of the upper and lower oil suction propeller wings 12a, 12b become smaller, so does the amount of the oil "O" being upwardly sucked resulting from the decreased centrifugal force and the thrust force.
However, in the oil suction propeller structure of the conventional hermetically-sealed compressor, as shown in FIG. 3, although the sucked-up amount of the oil becomes increased when the respective diameters of the oil guide piece and the oil suction propeller are increased, the oil portion that is in contact with the outer periphery of the oil guide piece may be whirled during the oil suction propeller rotation for thereby generating noise caused by a whirling and a dropping of the oil "O".
Further, when the respective diameters of the oil guide piece and the oil suction propeller are decreased for preventing the whiling and dropping noise, the centrifugal force and the thrust force are also decreased, for thereby deteriorating an oil supplying capacity.